From a5b56b167b6ab29875294ee11ccca801611eb065 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Tue, 24 Aug 2010 14:22:47 +0200
Subject: [PATCH] --- yaml --- r: 210278 b: refs/heads/master c:
 e41e704bc4f49057fc68b643108366e6e6781aa3 h: refs/heads/master v: v3

---
 [refs]                          | 2 +-
 trunk/include/linux/workqueue.h | 2 ++
 trunk/kernel/workqueue.c        | 7 ++++++-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 37a3ce87918e..0d4535bb0c97 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 972fa1c5316d18c8297123e08e9b6930ca34f888
+refs/heads/master: e41e704bc4f49057fc68b643108366e6e6781aa3
diff --git a/trunk/include/linux/workqueue.h b/trunk/include/linux/workqueue.h
index 4f9d277bcd9a..c959666eafca 100644
--- a/trunk/include/linux/workqueue.h
+++ b/trunk/include/linux/workqueue.h
@@ -241,6 +241,8 @@ enum {
 	WQ_HIGHPRI		= 1 << 4, /* high priority */
 	WQ_CPU_INTENSIVE	= 1 << 5, /* cpu instensive workqueue */
 
+	WQ_DYING		= 1 << 6, /* internal: workqueue is dying */
+
 	WQ_MAX_ACTIVE		= 512,	  /* I like 512, better ideas? */
 	WQ_MAX_UNBOUND_PER_CPU	= 4,	  /* 4 * #cpus for unbound wq */
 	WQ_DFL_ACTIVE		= WQ_MAX_ACTIVE / 2,
diff --git a/trunk/kernel/workqueue.c b/trunk/kernel/workqueue.c
index cc3456f96c56..362b50d092e2 100644
--- a/trunk/kernel/workqueue.c
+++ b/trunk/kernel/workqueue.c
@@ -87,7 +87,8 @@ enum {
 /*
  * Structure fields follow one of the following exclusion rules.
  *
- * I: Set during initialization and read-only afterwards.
+ * I: Modifiable by initialization/destruction paths and read-only for
+ *    everyone else.
  *
  * P: Preemption protected.  Disabling preemption is enough and should
  *    only be modified and accessed from the local cpu.
@@ -944,6 +945,9 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
 
 	debug_work_activate(work);
 
+	if (WARN_ON_ONCE(wq->flags & WQ_DYING))
+		return;
+
 	/* determine gcwq to use */
 	if (!(wq->flags & WQ_UNBOUND)) {
 		struct global_cwq *last_gcwq;
@@ -2828,6 +2832,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
 {
 	unsigned int cpu;
 
+	wq->flags |= WQ_DYING;
 	flush_workqueue(wq);
 
 	/*